Why does my Eevee renders freeze at 98%?
The only reason for this warning is that Blender is trying to read a TIFF.

Objects are not the only things that might use TIFFs. You might check your skydome or environment texture. If you have BlenderGuru's Pro-lighting Skies, then it's probably loading TIFFs at some point. You may have some other addon that uses TIFF images.

If you can upload a copy of your .blend file, someone here might be able to help you track down what images are causing the problem.